1. Field of the Invention
The present invention relates generally to hard copy printing and more specifically to a methods and devices for containing and feeding printing media in a drum type hard copy apparatus.
2. Description of Related Art
The art of hard copy printing technology is well developed in commercial products such as computer printers, graphics plotters, copiers, and facsimile machines. One specific type of hard copy printing employs ink-jet technology for producing the hard copy. The basics of this technology are disclosed, for example, in various articles in the Hewlett-Packard Journal, Vol. 36, No. 5 (May 1985), Vol. 39, No. 4 (August 1988), Vol. 39, No. 5 (October 1988), Vol. 43, No. 4 (August 1992), Vol. 43, No. 6 (December 1992) and Vol. 45, No.1 (February 1994) editions. Ink-jet devices are also described by W. J. Lloyd and H. T. Taub in Output Hardcopy [sic] Devices, chapter 13 (Ed. R. C. Durbeck and S. Sherr, Academic Press, San Diego, 1988). In order to explain the present invention, a ink-jet hard copy apparatus will be used as an exemplary embodiment. As the present invention may be extended to other forms of printing, no limitation on the scope of the invention is intended by the use of this exemplary embodiment nor should any such intention be implied.
FIG. 1 (PRIOR ART) depicts an ink-jet hard copy apparatus (with its cover shell removed, in this exemplary embodiment a computer peripheral printer, 101. A housing 103 encloses the electrical and mechanical operating mechanisms of the printer 101. Operation is administrated by an electronic controller 102, usually a microprocessor or application specific integrated circuit (xe2x80x9cASICxe2x80x9d) controlled printed circuit board connected by appropriate cabling to a computer (not shown). It is well known to program and execute imaging, printing, print media handling, control functions and logic with firmware or software instructions for conventional or general purpose microprocessors or with ASIC""s. Cut-sheet print media 105, loaded by the end-user onto an input tray 120, is fed by a suitable paper-path transport mechanism (not shown) to an internal printing station, or printing zone, 107 where graphical images or alphanumeric text is created. A carriage 109, mounted on a slider 111, scans the print medium. An encoder 113 is provided for keeping track of the position of the carriage 109 at any given time. At least one, or a set, of individual ink-jet pens, or print cartridges, 115x are releasable mounted in the carriage 109 for easy access. Generally, in a full color system, inks for the subtractive primary colorsxe2x80x94cyan, yellow, magenta (CYM)xe2x80x94and true black (K) (F standing for a fixer fluid) are provided in remote, or xe2x80x9coff-axis,xe2x80x9d replaceable or refillable, ink reservoirs 117x having fluidic couplings 119 to the pens 115x. Once a printed page is completed, the print medium is ejected onto an output tray 121. It is common in the art to refer to the pen scanning direction as the x-axis, the paper feed direction as the y-axis, and the ink drop firing direction as the z-axis.
Hard copy apparatus, be it in the form of a printer, plotter, copier, scanner, facsimile machine, or the like, share the need for having a blank printing media supply, preferably in an automated-feeder device appurtenant to the hard copy apparatus. In turn, printing media come in a variety of forms. A common computer printer 101, such as a Hewlett-Packard(trademark) DeskJet(trademark) ink-jet printer as depicted in FIG. 1, is usually designed to be compatible with a variety of media, such as plain paper, special paper, transparencies, and envelopes, up to and including legal size (8.5xc3x9714-inches) media as are commonly used in an office or home environment. On the other hand, a common large format plotter 201, such as an ink-jet plotter like the Hewlett-Packard DesignJet(trademark) series illustrated by FIG. 2 (Prior Art), requires accommodation for large sheets, or continuous, media 203, currently up to eighty inches in the scanning x-axis width dimension. As the computing arts expand into new fields, such as palm top computers or specialized computer printing needs, such as dedicated photograph ink printing as in the Hewlett-Packard PhotoSmart(trademark) digital camera 300 direct printer 303 series depicted by FIG. 3 (Prior Art), other sizes of printing media (e.g., 3.5xc3x975 for photographs) and other forms of recording media, such as cloth (e.g., for ink printing on T-shirts) and advanced automated-feeder devices are needed.
Herein, the terms xe2x80x9crecordingxe2x80x9d and xe2x80x9cprintingxe2x80x9d are used synonymously, intended to include the action of applying any type of colorant (e.g., ink, toner, and the like) to any kind of printing medium (e.g., paper, cloth, plastic, flexible materials, and the like)xe2x80x94referred to hereinafter generically as xe2x80x9cpaperxe2x80x9dxe2x80x94and any kind of hard copy producing apparatusxe2x80x94referred to hereinafter generically as a xe2x80x9cprinter.xe2x80x9d
One specific type of hard copy apparatus is generically referred to as a xe2x80x9cdrum printer.xe2x80x9d A schematic depiction of a drum printer 401 is shown in FIG. 4 (Prior Art). The operational functions of the printer are administered by an electronic controller 402, as would be known in the art, coupled to an input/output device 400, such as a computing apparatus. A drum printer 401 wraps a sheet of paper 403 from a provided supply 405 around a rotating cylinder 407 which then acts as a paper platen. A writing instrument 409 is located parallel to the drum surface or has a carriage (not shown), carrying one or more writing instruments as demonstrated by FIGS. 1 and 2, that travels along an axis parallel to the cylinder""s rotational axis. In a scanning carriage type drum printer, both carriage and drum velocities are held constant during printing to keep power consumption low and reduce dynamic operational problems, such as accounting for carriage reversal acceleration and deceleration ramp distances and durations during a print cycle. In general, drum printers have a higher throughput (xe2x80x9cpages per minutexe2x80x9d or xe2x80x9cppmxe2x80x9d) than flat bed scanning carriage printers such as shown in FIGS. 1 and 2.
Drum printers have design variations such as having a less than xe2x80x9cpage widexe2x80x9d, xe2x80x9cW,xe2x80x9d writing instrument stationary while the medium 403 rotates with the cylinder 407, moving the writing instrument only between printing each successive swath. Having the writing instrument stationary provides inherent print quality enhancing capabilities. The medium 403 does not cover the entire circumference of the drum; that is a gap, xe2x80x9cG,xe2x80x9d separates the medium""s leading edge 411 and trailing edge 413. The writing instrument is shifted quickly to start printing a next swath while this gap on the drum is passing. In another design variation, helical scanning by a writing instrument can be provided by slowing scanning the writing instrument carriage while the drum rotates or by translating the drum relative to a stationary writing instrument.
A main problem with drum printers is the loading and holding of the medium to the cylinder surface. Print quality may be degraded by variations of the medium registration to the drum surface. Manual taping or clamping is cumbersome and time consuming. Automated pick-and-feed mechanisms associated with an input tray combined with mechanical or electromechanical edge clamping devices improve the loading cycle time and eliminate the need for user intervention. Such mechanisms add significant complexity and cost to manufacture. Automated pick-and-feed mechanisms associated with an input tray combined with vacuum holddown cylinder drum printers are also known. Such vacuum systems also add significant complexity and cost to manufacture. Moreover, localized suction forces from the pattern of vacuum through-holes in the cylinder surface are generally transmitted through the printing medium and thus also can effect the print quality. Both automated clamping and vacuum systems compromise the desire for a small workplace footprint. Mechanical clamping requires precise timing. Vacuum systems require costly exhaust systems which also require a significant power supply.
All of the foregoing shortcomings of the prior solutions are exacerbated by the need to accommodate multiple printing media sizes. Mechanical holddowns may require segmented clamps coordinated with the current medium in use. Smaller width media on a vacuum holddown leaves vacuum ports in the cylinder uncovered, changing the suction flow dynamic. Maintaining the pressure difference necessary to hold the medium to the surface requires either higher air flow or adaptive mechanisms for closing uncovered ports.
There is a need for methods and devices for storing and holding printing media for a drum printer.
In a basic aspect, the present invention provides a print media cartridge device including: a supply of print media in a format such as a substantially cylindrical roll; a containing mechanism for containing the supply of print media in an interior chamber of the containing mechanism, wherein the containing mechanism is a substantially cylindrical construct having an outer surface for sequentially receiving at least one sheet of the supply thereon from within the containing mechanism via an aperture coupling the outer surface to the interior chamber; and mounting mechanism for mounting the print media cartridge device adjacent mechanisms for printing on the print media of a hard copy apparatus adapted for using the device.
In another basic aspect, the present invention provides a hard copy apparatus including: a writing instrument; mounted adjacently to the writing instrument, a removable, rotating drum platen having an outer surface, the outer surface including an aperture of a width sufficient for passing print media therethrough; a supply of print media contained within the drum in an orientation for continuously, sequentially feeding print media through the aperture such that at least one sheet length of the print media is wrapped around the drum platen when extracted from the drum; at least one mechanism for temporarily securing a leading edge of the sheet length wrapped around the drum platen to the outer surface such that the sheet length is positioned with respect to the writing instrument for receiving colorant therefrom; associated with the drum platen, at least one mechanism for encoding printing operation information; and associated with the writing instrument, at least one mechanism for recognizing the information.
In another basic aspect, the present invention provides a method of providing print media to a rotating drum type hard copy apparatus including the steps of: providing the apparatus with a replaceable rotating drum construct mountable on the apparatus and having a supply of print media contained within the drum construct, wherein the supply of print media is in a form such that the media is extractable from within the drum construct via an aperture in an outer surface of the drum, the outer surface configured for holding predetermined lengths of the media extracted from within the drum construct such that the surface forms a printing platen in the apparatus; and periodically replacing the rotating drum construct with a rotating drum construct cartridge having a replacement supply of print media therein.
In another basic aspect, the present invention provides a method of providing print media to a rotating drum type hard copy apparatus including the steps of: providing the apparatus with a refillable rotating drum construct mountable on the apparatus and having a supply of printing media contained within the drum construct, wherein the supply of printing media is in a form wherein the media is extractable from within the drum construct via an aperture in an outer surface of the drum, the outer surface configured for holding predetermined lengths of the media extracted from within the drum construct such that the surface forms a printing platen in the apparatus; and periodically replacing the supply of printing media drum within construct with a replacement supply of print media therein.
In another basic aspect, the present invention provides a method of producing hard copy including the steps of:
a) providing a drum platen with an internal supply of a continuous printing medium;
b) extracting through the drum platen a first length of printing medium from the supply by a leading edge;
c) wrapping the first length about the drum platen;
d) securing the leading edge of the first length to the drum platen proximate a trailing edge of the first length;
e) printing on the first length by rotating the drum platen in a first direction passed a writing instrument;
f) releasing the leading edge;
g) pulling the first length away from the drum platen wherein the drum platen is rotated in a second direction opposite the first direction;
h) stop locking the drum platen in a predetermined position wherein the step of pulling further extracts a next length of printing medium from within the drum platen;
i) separating the first length from the next length;
j) rotating the drum platen in the first direction such that the next length is wrapped around the drum platen;
k) securing the leading edge of the next length to the drum platen proximate a trailing edge of the next length; and
l) repeating steps e) through k) for each hard copy to be produced.
Some advantages of the present invention are:
the present invention provides a compact and low cost printing media cartridge for a drum printer;
the present invention provides a disposable or reloadable printing media cartridge having recognizable encoding for printing operation controls;
the present invention provides a printing media cartridge that also serves as a drum platen for a drum printer;
the present invention provides a simple mechanism for loading a recording medium into a hard copy apparatus;
the present invention provides a disposable mechanism for loading a recording medium into a hard copy apparatus;
the present invention provides a replaceable mechanism for loading a recording medium into a hard copy apparatus;
the present invention provides manufacturer-loadedable, reliable printing medium supplies;
the present invention provides a mechanism for encoding printing medium types and printing characteristics, automatically recognizable by a hard copy apparatus;
the present invention provides for a printing medium encoding scheme that can use the same sensor used for drum speed control; and
the present invention provides for a low cost solution to drum printer supply and loading procedures.
The foregoing brief summary of the basic aspects of the invention and list of advantages is not intended by the inventors to be an inclusive list of all the aspects, objects, advantages and features of the present invention nor should any limitation on the scope of the invention be implied therefrom. This Summary is provided in accordance with the mandate of 37 C.F.R. 1.73 and M.P.E.P. 608.01(d) merely to apprize the public, and more especially those interested in the particular art to which the invention relates, of the nature of the invention in order to be of assistance in aiding ready understanding of the patent in future searches. Other objects, features and advantages of the present invention will become apparent upon consideration of the following explanation and the accompanying drawings, in which like reference designations represent like features throughout the drawings.